A book embedding is an emebdding of a graph into a collection of half-planes ("pages" or "leaves") that share a common boundary line (the "spine" or "back"), where each edge must be drawn on a single page.
The smallest possible number of pages for a book embedding of a given graph is known
as its book thickness.
Heath, L. S. "Algorithms for Embedding Graphs in Books." PhD thesis. Chapel Hill, NC: University of North Carolina, 1985.Numberphile.
"Discovery About Book Embedding of Graphs." Apr. 30, 2023. https://www.youtube.com/watch?v=qw2Pl_Nk3CA.